ISO 2484:1973

The principle of the method consists in dissolution of a test portion previosly ground and sifted. Acidification to pH 1 after suitable dilution and atomization of the resultant solution in the burner of a flame spectrophotometer. Determination of the potassium content by measurement of the intensity of the radiation emitted at 766 nm. Comparison with the intensity of standard potassium chloride solutions acidified in the same way.